Diaphragm pump and pump for double-breast pumping

ABSTRACT

A motorized pump is disclosed that includes a flexible diaphragm fitting within a rigid member, a motor drive mechanism for drawing a puller member attached to the diaphragm away from the rigid member to create a space between the diaphragm and the rigid member and form a negative pressure region within that space, and an outlet communicating with the negative pressure region. In one embodiment, the pump provides a negative pressure in a single chamber which can be used to operate one or two breast shield assembles. In another embodiment, the pump is particularly adapted for double-pumping and provides two chambers which generate vacuum.

RELATED PATENT APPLICATIONS

[0001] This patent application is a continuation-in-part of U.S. Ser.No. 08/510,714 filed Aug. 3, 1995.

BACKGROUND OF THE INVENTION

[0002] The invention relates to motorized pumps, and more particularly,to breastpumps.

[0003] Breastpumps are convenient for nursing mothers, because, amongother things, they allow the nursing mother to draw off breast milk tofeed to the child at a later time when the mother may not be present.For some mothers, breastpumps are required, particularly when the childhas suckling difficulties, or if the mother has problems with excessiveor deficient milk production, or cannot empty completely. Some mothersalso require breastpumps in the event of soreness or injury of themammilla, or sunken mammilla.

[0004] Manually-driven breastpumps are commonplace. However, theytypically require the use of both hands to pump a single breast—one tohold the breast shield/pump in place, and the other to drive the pump.There are also manually driven breastpumps that can be operated with onehand, as by using a lever-type drive mechanism. They also obviouslyrequire some manual effort to operate.

[0005] Motor-driven pumps for breastpumps, such as battery-powered orhouse-current powered, also have been marketed. While eliminating theneed for manually reciprocating the pumping mechanism, those pumps madefor operating two breast shield assemblies at once—double-pumping—havetypically been quite large, and often quite heavy. Smallerbattery-powered pumps which are part of the breast shield assemblyitself have not historically been adapted to, or capable of,double-pumping off the same pump.

SUMMARY OF THE INVENTION

[0006] The present invention was designed with many of the foregoingconsiderations in mind. It has a principal objective to provide arelatively inexpensive but efficient pump that is readily portablebecause it is compact and lightweight.

[0007] The motor drive mechanism of the pump has a durable drive train,and the main vacuum-generating pump components—flexible diaphragm andrigid cap—are each preferably detachably mounted together within aframe. Assembly, and disassembly—as for repair or cleaning—are thereforeefficiently and easily accomplished. A pressure regulator valvemechanism on the rigid cap further provides simple manual control forvarying negative pressure developed by the pump.

[0008] These features make the inventive pump ideally suited for abreastpump. More particularly, the present invention in one form is anelectrically-powered diaphragm pump mounted within a support framecontained in a soft carrying case. A zippered flap in the carrying caseprovides access to the front of the pump unit, which has spigots forattaching tubing that connects to breast shield assemblies.

[0009] The diaphragm pump in one form of the invention has a durabledrive chain comprising a drive shaft fit with an eccentric cam, to whichis attached a follower. The follower is in turn pivotably connected to apuller that is attached to a flexible diaphragm. The diaphragm restsnear or against the interior surface of a rigid cap, the latter beingstationarily mounted. An expansible chamber is thus provided. Inoperation, the rotation of the drive shaft rotates the cam, causing thefollower to move back and forth as it orbits the shaft. The puller moveswith the follower, drawing the diaphragm away from the cap and forming anegative pressure that is communicated by one or two spigots to tubingattached to the breast shield assemblies.

[0010] It is also contemplated that the foregoing drive mechanism beadapted to drive two diaphragms in respective cap assemblies. In onesuch an embodiment, the puller would take the form of a yoke to whichthe diaphragms are connected. The follower would then reciprocate tomove the puller and associated diaphragms toward and away from the caps.In another such embodiment, a pair of opposed pullers would be used in apush-pull arrangement, whereby the two pumps cycle oppositely. Ofcourse, this diaphragm and cap assembly is but one type of expansiblechamber pump that could be advantageously used with other aspects of theinvention.

[0011] The pump further can include a vacuum regulator device on thecap. The regulator device can also be located elsewhere, such asanywhere between the breast shield and the vacuum source, or on thebreast shield itself. In one embodiment, the vacuum regulator comprisesa rotary valve member mounted for rotational movement on the rigid cap.An aperture is formed through the valve member. At least one hole orrecess is formed through the cap member, and communicates with thepressure region generated between the cap interior and the diaphragm.

[0012] The valve member has a first position wherein the valve apertureand the cap hole are aligned to place the pressure region incommunication with atmosphere, and a covered position wherein the valveaperture and the cap hole are unaligned, with the valve member therebyclosing the cap hole. A maximum and minimum vacuum level are therebyprovided, depending on whether air can be drawn within the cap or not,as controlled by the valve.

[0013] A second hole different in size from the first cap hole can beadditionally provided, establishing a second position wherein the valveaperture and the second cap hole are aligned for a different vacuumlevel. Maximum, medium and minimum vacuum levels can thus be madeavailable through adjustment of the cap hole sizes.

[0014] The foregoing vacuum regulator device has further been modifiedin another embodiment. In the latter form, the rotary valve member has acrescent-shaped channel formed in its base (the part that is in contactwith the cap). The aperture through the valve member extends into thischannel. Two cap holes are formed in the cap. In the minimum vacuumposition, the channel overlies both cap holes; in the medium position,only one hole, and in the maximum vacuum position, neither cap hole isin communication with the channel.

[0015] In yet another embodiment, the vacuum regulator device takes theform of a ring element which is rotatably mounted on each of a pair ofcaps in a pump adapted for double breast pumping. The rotatable elementis easily manipulated. This also enables independent control of thevacuum being generated in each breast shield assembly, for maximumconvenience of the mother. The previously noted vacuum regulator devicesabove can likewise be used on each of the pump caps for the sameadvantageous independent control. Also, a continuously variable vacuumregulator device has been developed and can be used.

[0016] In a further evolution and adaptation of the foregoing inventionutilizing a diaphragm pump, an apparatus has been developed which isparticularly adapted for double breast pumping (although, and as will beseen, single breast pumping is also plainly included within its ambit).

[0017] In a first form of this adaptation, a double-diaphragm pumpingmechanism has a pair of opposed pressure-generating units, in particularfor generating a negative (vacuum) pressure. In a presently contemplatedembodiment, one unit is adapted for direct attachment to a breast shieldassembly. This unit has a diaphragm mechanism which is inserted into areceptacle, or collar, formed as part of the breast shield assembly.With the collar, the diaphragm forms a chamber within which a vacuum isgenerated. The other unit in this embodiment is self-contained, i.e., ithas a diaphragm mechanism located within a rigid cover to form another(second) chamber within which a vacuum is generated. An outlet port isprovided for communicating the vacuum this second chamber is generating.That outlet port is connected by tubing to another breast shieldassembly.

[0018] A common drive mechanism serves to operate both of the pressurechambers of this double-diaphragm pump. In the foregoing embodiment, thedrive mechanism uses an offset push-pull arrangement to createalternating negative pressure in the respective chambers. This resultsin alternating suction on the breasts. The double-diaphragm pumpingmechanism of this embodiment (which is mounted to a breast shieldassembly) is compact and light enough to be readily supported on asingle hand-held breast shield assembly, such that it can be held inplace by the mother on one breast with one hand, while the other breastshield assembly, which is being run off of the same pump, is held inplace with the other hand.

[0019] In another form of this adaptation, the double-diaphragm pumpingmechanism again has a pair of opposed pressure chambers, except they arebuilt into a small lightweight housing, such as might be set upon atable rather than held in the hand. This pumping mechanism utilizes apair of opposed pressure chambers and a push-pull drive arrangement toalternately create a negative pressure in a respective chamber. Anoutlet is provided for each chamber which is connected via tubing to arespective breast shield assembly.

[0020] In a presently contemplated embodiment, the foregoing pumpingmechanism further includes a speed regulator device for controlling therate of pumping (i.e., the suction cycle or timing between negativepressure events). The “table-top” version also has a sound-deadeningconstruction molded into the housing.

[0021] Other features and advantages of the present invention willbecome apparent from the detailed description that follows taken inconjunction with the drawings, described below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a perspective view of a first embodiment of a diaphragmpump-driven breastpump made in accordance with the present invention;

[0023]FIG. 2 is a cross-sectional view of the breastpump of FIG. 1within a closed carrying case;

[0024]FIG. 3 is an exploded perspective view of most of the elements ofthe diaphragm pump;

[0025]FIG. 4 is a perspective view of a follower;

[0026]FIG. 5 is a cross-sectional view along line 5-5 of FIG. 4;

[0027]FIG. 6 is a perspective view of an alternative embodiment of aguide for the diaphragm pump;

[0028]FIG. 7 is a front view of the diaphragm pump cap of the firstembodiment;

[0029]FIG. 7A is a modified form of a vacuum regulator;

[0030]FIG. 7B is a front view of another embodiment of a vacuumregulation device;

[0031]FIG. 7C is an enlarged view of the rim upon which a disk valverotates in the embodiment of FIG. 7B;

[0032]FIG. 7D is a disk valve for use with the rim of FIG. 7C;

[0033]FIG. 7E is a side view partly in section of the embodiment of FIG.7B;

[0034]FIG. 8 is an enlarged partial view in section of the diaphragmpump mounting arrangement shown in FIG. 2;

[0035]FIG. 9 is an enlarged partial view in section of an alternativeform of the diaphragm;

[0036]FIG. 10 is a perspective view of a cap for use with the pumpspigots.

[0037]FIG. 11 is another embodiment of the invention in the form of apump for double breastpumping;

[0038]FIG. 12 is an enlarged sectional view of the breastpump of FIG. 11having the pumping units attached thereto;

[0039]FIG. 13 is yet another embodiment of the invention taking the formof a tabletop version;

[0040]FIG. 14 is a sectional view taken along line 14-14 of FIG. 13;

[0041]FIG. 15 is a sectional view taken along line 15-15 of FIG. 13;

[0042]FIG. 16 is an enlarged view of the pump of FIG. 13, with thevacuum adjusting ring removed;

[0043]FIG. 17 is a perspective view of the interior of the half of thepump casing facing away from the viewer in FIG. 16;

[0044]FIG. 18 is a perspective view of the other half of the pump casingof FIG. 16;

[0045]FIG. 19 is a side view of another design for an embodiment of theinvention;

[0046]FIG. 20 is a side view of yet another design for an embodiment ofthe invention; and

[0047]FIG. 21 is a perspective view of still another embodiment for apump for double breast pumping.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0048] A diaphragm pump of the present invention is shown in embodimentsas a vacuum (i.e., negative pressure) source for a breastpump. Thediaphragm pump has uses in other environments and applications, however.

[0049] Referring to FIG. 1, a first embodiment of a diaphragm pump 10according to the present invention is mounted within a rigid supportframe 12. The support frame 12, which is somewhat boxlike, is carriedand mounted within a soft carrying case or bag 14. It is shown connectedto two breast shield assemblies 16 via tubing 18. Tubing 18 is attachedat one end to respective spigots 20 (FIG. 2) via a slip-on fit over thespigots 20. With the tubing 18 removed from the spigots 20, thediaphragm pump 10 can be closed up within the case 14 via a zipperedflap 22. Front plate 24 of the pump 10 may preferably be set back fromthe sidewall of the case 14 so that the zippered flap 22 is co-planarwith the case front sidewall 14 a when shut, although it need not be soinset. A wall 21 is formed surrounding the spigots 20 to protect thespigots from being accidentally broken off.

[0050] Case 14 has a number of interior compartments 26 a, 26 b, 26 c,which constitute storage areas, such as for the breast shield assemblies16, tubing 18, diapers, etc. Case 14 also could include a power sourcein the form of a battery (not shown) to which a commonly obtainable 12VDC gear motor 28 (FIG. 2) is electrically connected. An alternativepower source could be an A.C. source (e.g., common 120 VAC service)through a DC converter, as at jack 27 (FIG. 1). The motor, power sourceand their various electrical connections are all conventional, and wellknown to those skilled in the art.

[0051] Case 14 has a flap-type closure 30, with a shoulder strap 32.Pump support frame 12 is fixed within a fabric compartment formed withinthe case 14. This may be by attachment of the front plate 24 tosurrounding fabric 14 b in a conventional manner, such as by riveting,stitching, adhering or some other common attachment. Here, front plate24 frames the fabric 14 b and captures it between the back of the plate24 and the front 12 a of the support frame 12. This is accomplishedusing toothed plastic rivets 34, or alternatively keyhole-typefasteners, which extend through the front plate 24, holes in theintervening fabric 14 b, and then through holes provided in the front 12a of support frame 12.

[0052] The breast shield assemblies 16 are of the type sold by Medela,Inc. under the name MANUALECTRIC, and generally shown in U.S. Pat. Nos.4,857,051 and 4,929,229, for example. The assemblies 16 have a breastshield 36 associated with a milk bottle 38. A periodic vacuum generatedby the pump 10 within the shield 16 serves to extract milk, which isthen collected in the bottle 38.

[0053] Pump 10 has a guide 40 (FIG. 3) fixedly mounted to an inner framewall 12 b (FIG. 2), as by machine screws (not shown) with hole 41provided to this end. An opening 42 is made in the guide 40 throughwhich drive shaft 44 of the motor 28 extends. The diameter of theopening 42 is wider than the drive shaft 44 so that the latter freelyrotates. Guide 40 has an elongated slot 45 formed therein which servesto confine and direct the movement of a guide pin 46 extending from apuller 48 connected to a follower 50 in a manner to be describedhereafter.

[0054]FIG. 6 illustrates an alternative embodiment for the guide. Guide40′ functions in the same manner as guide 40. It is mounted to the innerframe wall 12 b (FIG. 2) using machine screws through holes 41′, and hasan elongated slot 45′ for the guide pin 46. Drive shaft 44 extendsthrough hole 42′. Prime numbers used herein describe generally similarelements to their unprimed counterparts.

[0055] A cam or eccentric 52 is mounted on the drive shaft 44 (FIGS. 2and 3). A collar-like portion 53 is formed off-center on the cam. Theoutboard end of the drive shaft 44 is received in a D-shaped opening 54within the collar portion 53, with the drive shaft 44 keyed to the sameshape in a snug fit. An e-clip or c-clip (not shown) can be attached tothe end of the shaft to further secure the cam 52 on the shaft.

[0056] An aperture 56 is also formed off-center in the cam 52. When cam52 is driven by the motor 28 turning the drive shaft 44, aperture 56orbits around the drive shaft 44. Of course, and as will be evident fromthe further description below, the cam-and-drive shaft mechanism couldbe made to turn in less than 360° or reciprocate, and still achieve thedesired movement.

[0057] Follower 50 (FIG. 3) is operably connected to the cam 52 via ahollow post 58 formed adjacent the rearward end of the follower 50. Post58 has a diameter which is slightly smaller than that of the aperture 56of the cam 52 within which it is received to freely rotate. For purposesof relative scale, the follower 50 shown herein has a longitudinallength of about 2.5 inches, and a lateral width of about 0.75 inch. Amachine screw, washer and lock-nut combination 57 is additionally usedfor further, but movable fixation (FIG. 2). An alternative embodiment offollower 50 is shown in FIGS. 4 and 5.

[0058] On the forward end of the follower 50 is mounted the puller 48(FIG. 3). Puller 48 has two parallel legs 49 which extend from a pullercap 59 (FIG. 9) formed of an end disk or button 60 and a disk-likeflange 61 spaced slightly inboard from the end disk 60. Puller 48 isconnected to the follower 50 via a spring pivot pin 62 (FIG. 3) whichextends through and is fixed within holes 63 in the legs 49 (only one ofwhich holes 63 is shown in FIG. 3), and extends through hole 64 in thefollower 50. The follower 50 is thus captured between the legs 49, butcan pivot on the pivot pin 62. A guide pin 46, which is fixed withinholes 65 a, 65 b in the legs 49, extends through a crescent-shapedaperture 66 formed in follower 50 (FIG. 3). When the follower 50 ismounted to the cam 52, guide pin 46 extends into the slot 45 of theguide 40 (FIG. 2).

[0059] A flexible diaphragm 70 is mounted on the end of the puller 48.Diaphragm 70 is preferably made of silicone, which could be rated forfood contact but need not be, and has a general semi-spherical shape.End disk 60 (FIGS. 2 and 9) of the puller 48 is received within anorifice in the inboard side of the diaphragm 70, which orifice is formedby a thickened center part of the diaphragm 70 and a circular overlyingflange part 72 (FIG. 2, and see detail of connection in FIG. 9). Enddisk 60 fits within this orifice in a button-like engagement. Flangedisk 61 on the puller 48 presses against the flange part 72 of thediaphragm to further enhance the engagement. Alternatively, thediaphragm 70 could be molded integral with the end of the puller. Itwill be noted that a circumferential reduced wall thickness is formed inthe diaphragm at 70a around the center area of the diaphragm 70 tofacilitate flexion of the diaphragm. The wall thickness of the portionof the diaphragm 70 between the thickened center part and approximatelythe perimeter of the curved portion of the diaphragm is generally about0.08 in.

[0060] An alternative form for the diaphragm wall is shown in FIG. 9. Asshown in that figure, a corrugated or rippled interior provided byconcentric channels 71 facilitate flexion of the diaphragm 70.

[0061] As shown in FIGS. 2 and 8, diaphragm 70 is mounted to the frontplate 24 using a diaphragm mounting ring 74. Diaphragm 70 has aperimetrical shoulder 76 formed thereon from which depend inner andouter concentric circular flanges 78 and 80, respectively. With shoulder76, flanges 78 and 80 form a circular channel. The outboard part ofmounting ring 74 is received within this channel in a slip-on type fitof the diaphragm.

[0062] With the diaphragm 70 so mounted thereon, mounting ring 74 isreceived in an aperture formed in the front plate 24 and the frame front12 a. Two locking tabs 82 a, 82 b (FIGS. 2 and 8) extend outwardly atopposite sides of the mounting ring, and engage within cut-outs formedin the aperture of the frame front 12 a to position the mounting ring byrotating the mounting ring into place.

[0063] A thin-width radial ring 84 (FIG. 8) is formed around the outsidecircumference of the mounting ring 74. This ring 84 underlies anoutwardly extending lip 79 provided on the diaphragm 70, which lip 79 ispressed between the front plate 24 and the ring 84.

[0064] Overlying the diaphragm 70 (FIG. 8) is a rigid housing cap 86(FIG. 2) made of polypropylene. Cap 86 has an inner surface roughlymatching the curvature of the diaphragm 70, such that the diaphragmrests close to or against the interior surface of the cap 86. The cap 86has a ring-like portion 89 extending outwardly from the edge of thesemi-spherical dome portion of the cap 86. Concentric inner and outercap flanges 88 and 90, respectively, depend from the ring-like portion89 (see FIGS. 7 and 8 in particular). Inner cap flange 88 pressesagainst the outboard side of outer diaphragm flange 80, with part ofring-like portion 89 overlying diaphragm shoulder 76. In conjunctionwith the mounting ring 74, this forms an air seal between the cap 86 andthe underlying diaphragm 70. Additional concentric ribs 87 a, 87 b(FIGS. 8 and 9) are formed on top of the diaphragm shoulder 76 out ofthe same material as the diaphragm, and serve to facilitate this sealthrough compression against the cap shoulder 89. Outer flange 90 of thecap 86 is received in a snap-engagement with a cap mounting ring orcollar 92 formed on the face of the front plate 24 to mount the cap 86in place.

[0065] It will be recognized that the diaphragm 70 is one element thatis moved relative to another member or base (the cap 86) to form anexpansible chamber that has an expanding and contracting volume. Othersuch expansible chambers are considered to be adaptable to aspects ofthis invention, although the flexible diaphragm and cap arrangement hasproved most advantageous at this time.

[0066] In operation of the pump 10, motor 28 is actuated, as by astandard on-off circuit utilizing switch 94 mounted in the front plate24. Drive shaft 44 rotates cam 52 causing follower 50 to move rearwardly(relative to the front plate 24) and then forwardly. Puller 48 in turnmoves rearwardly with the follower 50, drawing diaphragm 70 away fromthe inside of the cap 86. This generates a negative pressure (vacuum) inthe space thus formed between diaphragm 70 and cap 86 (see dotted-lineposition of the drive chain elements and diaphragm in FIG. 2).

[0067] The rotation of the cam 52 with its movement of the pivotablefollower 50 is designed to generally generate and follow the type ofvacuum curve, and cycles per minute, shown and described in Medela U.S.Pat. No. 5,007,899. Guide 40 serves to constrain the pivoting movementbetween the puller 48 and follower 50.

[0068] The negative pressure generated within the cap 86 is communicatedthrough the outlet provided by the spigots 20 to one or both of thetubes 18 (depending on whether one or two breast shield assemblies 16are being used). If only one breast shield assembly 16 is being used, itis contemplated that a cap 102 (FIG. 10) would be used to close thespigot 20 not being used. The cap 102 would further include a small venthole 103 designed to nonetheless admit some air through the spigot andthereby into the cap interior in a manner to normalize the vacuumbetween single and double pumping usage, i.e., so that the vacuum drawnin a shield is about the same when only using one breast shield as whenboth breast shield assemblies are attached. Cap 102 has a loop end 104to tether the cap 102 to one of the spigots 20.

[0069] A vacuum regulator is additionally provided for adjustment of thelevel of vacuum from the pump. This regulator takes the form of aflap-type valve disk 95 (FIG. 7) mounted in a circular-shaped depressionformed in the center of hemispherical diaphragm cap 86. Valve disk 95has a knob 96 (FIG. 2) which is received in a lipped aperture 97 formedin the foregoing depression, in a pop-in fit. A knurled stem 98 extendsfrom the valve disk 95 which is grasped to rotate the valve.

[0070] When valve disk 95 is rotated, a hole 100 through the disk 95 canbe aligned with one or the other of holes 99 a, 99 b (FIG. 7) extendingthrough the depression into the interior of the cap dome, or placed outof alignment with either hole 99 a, 99 b, the latter both then beingcovered and closed by the valve disk 95. Holes 99 a and 99 b are ofdifferent diameters, such that more air will pass through one than theother when aligned with disk hole 100. Accordingly, a preset “medium”(smaller diameter hole), “minimum” (larger diameter hole) or “maximum”(both holes covered) vacuum level range is provided. Crescent-shapedaperture 101 formed through the cap 86, which is under the disk valve95, serves to vent air admitted into the cap interior (within thediaphragm/cap space created by the vacuum stroke) on the forward orcompression stroke of the diaphragm 70 (diaphragm 70 moving toward thecap interior).

[0071]FIG. 7A shows a modified form of a vacuum regulator similar inconcept to that of FIG. 7. In this form, hole 100 is formed through thedisk 95, but extends into a crescent-shaped channel 105 formed in theunderside of the valve disk, i.e., the part in facial engagement withthe cap 86. As in the previous version, the disk 95 is located in ashort well 106 defined by a collar (see FIG. 2). Disk 95 is rotated sothat the channel 105 can be put in communication with one hole 99 a,both hole 99 a and 99 b, or neither hole, for medium, minimum andmaximum pressure, respectively. Also, a vent or leakage groove 107 isprovided in the well beneath the disk 95 from a hole 99 a and extendinginto and upwardly out of the collar 106. This provides a desirableamount of constant air leakage into the cap even at maximum negativepressure. This air leakage assures that there will be some air withinthe cap to apply a positive pressure on the return stroke, which can beused as a pneumatic assistant to move milk from a catch chamber into thecontainer.

[0072] Yet another form of vacuum regulation device is shown in FIGS. 7Bthrough 7E. In this embodiment, a rotatable regulator disk valve 200fits upon a rim or collar 201 formed on the rigid cap 86″. A channel orrecess 202 is formed on the outside of the rim 201. The channel is ofconstant width but of increasing depth (going from bottom to top asviewed in FIG. 7C). A port or hole 203 is in the deepest part of thetapered channel 202, and extends through the cap 86″.

[0073] Disk valve 200, which can be made of a somewhat flexible rubbermaterial, has a nub 204 that fits within an appropriately sized apertureformed in the rim/cap, with a collar 204 a that catches against asidewall edge defining the aperture to rotatably mount the disk valve200 in place. On the inside of the disk valve sidewall 200 a is a recess206 which communicates with atmosphere.

[0074] Thus, with the disk valve 200 turned so that its recess 206 islocated over the shallowest part of the rim channel 202 and furthestfrom the hole 203, air “leakage” into the cap 86″ interior—through thedisk valve recess 205 into the rim channel 202 and through the hole203—is at a minimum. As the disk valve 200 is rotated so that its recess206 is located at a deeper part of the channel 202, air flows morefreely to the hole 203 and into the cap interior, toward a maximum whenthe recess 206 is over the deepest part of the channel 202 adjacent hole203. A continuously variable vacuum regulating device is therebyprovided.

[0075] A diaphragm pump is thus provided which is of relatively smallsize, with a durable drive chain. In the disclosed environment of abreastpump, it fits handily within a soft carrying case for quick andeasy hook-up to one or more breast shield assemblies, which can becarried in the case.

[0076] It is envisioned that a thin disposable membrane-like cover (notshown) may additionally be provided over the diaphragm 70. Thisdisposable cover would be between the diaphragm 70 and inside of the cap86, and serve to further hygienically isolate the diaphragm 70 from anymilk, air or the like which could be pulled within the cap 86 in thevacuum stroke. This disposable cover would be particularly useful ifthere were multiple users of the pump 10. Cap 86 would simply be removedand sterilized, and the disposable cover replaced between users.Alternatively, a separate cap 86, which itself might be disposable, foreach user with a disposable cover could be provided.

[0077] Turning now to FIGS. 11 and 12, another embodiment of theinvention takes the form of a double-diaphragm pump, i.e., a pump thathas two diaphragms, which is particularly adapted for double-pumping(although, as will be seen, it also has a single-pumping mode ofoperation). The double pump is generally shown at 110. It communicatesvacuum (as will be described below) to breast shield assemblies 16′(again, prime numbers indicate generally similar elements to theirunprimed counterparts). Breast shield assemblies 16′ include a vacuumregulator 112 which modifies the amount of reduced pressure generated bythe pumping action. The regulator 112 comprises a rotary member 113 withan internal groove or passage 115. The rotary member 113 has hollowends. One hollow end encircles a ported structure 114 in the form of anub having a pair of holes or ports (not shown). The rotary member 113fits within a cavity 116 formed in the breast shield assembly 16′. Theported nub 114 is at one end of the cavity, and a boss 117 is at theother end. The other hollow end of rotary member 113 is received on theboss 117 to rotate thereon. Reduced pressure is adjusted by positioningthe internal groove 115 of the rotary member 113 over one, both orneither of ports of the ported nub 114. The internal groove 115 is opento atmosphere. The ports extend into the interior of the breast shieldassembly 16′. Depending upon whether the internal groove 115 is over oneport or both ports, suction or reduced pressure is thereby modified byallowing air to bleed into the breast shield assembly 16′ through thevacuum regulator 112. The regulator 112 is easily rotated, andconveniently located, allowing the user to manipulate it with onefinger, if desired.

[0078] A valve mechanism 118 is located at the lower portion of catchchamber 119. The valve mechanism 118 is described in U.S. Pat. No.4,929,229, with a flexible disk 125 mounted to cover openings in a valvehousing 126 in a flap-valve fashion. When the breast pump is operated,the disk 125 is caused to close underlying apertures in the valvehousing 126 under negative pressure, thus closing the collection chamber119. When the vacuum is released, milk collected in the collectionchamber 119 flows downwardly into the container 38 through the aperturespast the disk 125. The valve housing 126 may be attached to the outsideof a short tubular extension of the collection chamber 119 via a snuginterference fit.

[0079] The double-diaphragm pump 110 is adapted to be carried by one ofthe breast shield assemblies 16′, enhancing its portability. To thisend, one or (as shown here) both of the assemblies 16′ has an enlargedcollar or skirt 120 formed thereon, which is in communication with theshield 36 via orifice 121. This collar 120 forms a generallyhemispherical rigid shell much like that of rigid cap 86 of theembodiment described in regard to FIG. 2, for example, and functioningto the same end. A rigid cap 122 is also provided for thedouble-diaphragm breast pump 110, which again is similar to that of therigid cap 86 in function, as discussed hereafter.

[0080] As shown in FIG. 12, the double-diaphragm pump 110 has a motor124, which in this embodiment is a suitable DC gear motor. Motor 124 isfixedly mounted to a pump housing 128. Pump housing 128 is generallycylindrical (tubular), with radially extending disk-shaped mountingflanges just inboard from each end. The motor 124 extends through and isheld within a motor mount 131 formed by a hole extending through theside of the housing body 128. A motor cover (not shown) would preferablysurround the motor 124.

[0081] A drive shaft 44′ extends from the motor 124 and is rotated bythe motor. Fixed to the drive shaft 44′ is an eccentric element 52′.Fixed to and extending from the eccentric 52′ is a pin 134, whichfunctions much like the post 58 of the aforedescribed embodiment of FIG.2. That is, as eccentric 52′ is rotated by the drive shaft 44′, the pin134 will orbit the drive shaft.

[0082] Mounted upon the pin 134 are a pair of pullers 48′. Each puller48′ has a pair of parallel legs 49′. Holes 65 a, 65 b are provided ineach of the legs through which the pin 134 is received. The pin 134rotates freely within the holes 65 a, 65 b. It will be noted that thepullers 48′ extend in opposite directions, with the legs 49′ of thepullers staggered when mounted on the pin 134. A spacer 136 is usedbetween two legs of the respective pullers 48′. A retaining nut 134 ismounted on the free end of the pin 134 to retain the pullers 48′ inplace.

[0083] In this embodiment, a flexible diaphragm 70′ is fixed in place,as by insert molding, silicone glue or the like, to an end disk 60′ ofeach puller 48′. One of the diaphragms 70′ is received within thehemispherical shell formed by collar 120. This is accomplished using adiaphragm mounting ring 74′ having an upstanding collar or shoulder 76′.Lip 80′ of the diaphragm 70′ (FIG. 12) fits over the outboard side ofthe shoulder 76′ in an airtight engagement. When this diaphragm 70′ isinserted within the collar 120, its flange 80′ is pressed between theinboard side of the collar 120 and the outboard side of the shoulder76′, in essence forming a gasket. This seals its engagement with thecollar 120, and retains the pump 110 within the breast shield assembly16′. An identical mounting arrangement is used for the other diaphragm70′ within the rigid cap 122.

[0084] Of course, the mounting arrangement for the diaphragm 70′ couldalso be adapted in a manner as shown in FIG. 8. The diaphragm could alsobe glued to the ring 74′.

[0085] In operation of the embodiment of FIGS. 11 and 12, one of thediaphragms 70′ of the double-diaphragm pump 110 is mounted within thecollar 120 of a breast shield assembly 16′. A rigid cap 122 is placedover the other diaphragm 70′. When the motor 124 is actuated, each ofthe diaphragms 70′ is caused to reciprocate, thereby generating anintermittent vacuum (negative pressure) in its respective breast shield36. This vacuum will obviously alternate between the breasts.Reciprocation is accomplished through the action of the pin 134 as itrevolves with the eccentric 52′, pulling one puller 48′ and pushing theother.

[0086] With respect to the vacuum being generated within the rigid cap122, it is communicated to the remote breast shield assembly 16′ viatubing 18. One end of the tubing 18 is connected to a spigot 138 formedwith the cap 122, and a spigot-like adapter 139 inserted into the othertube end and into an aperture formed in the collar 120. Of course, ifonly one breast is to be pumped at a time, the tubing 18 need not beconnected, and the cap 122 can simply be vented to atmosphere.

[0087] Yet another double-diaphragm embodiment is shown in FIGS. 13through 17. This takes the form of a table-top version, generallyindicated at 150. In this embodiment the double-diaphragm pump islocated within a two-piece rigid housing having housing halves 151 a and151 b. Formed integral with each housing half is a diaphragm mountingring 74″ (FIG. 14) with upstanding collar or shoulder 76″. Receivedthereon is a respective diaphragm 70″. The diaphragms 70″ can mostpreferably be integrally molded with the housing halves. A hemisphericalrigid cap 122′ is provided for each housing half, and serves to form anairtight engagement with the diaphragm 70″ in the same manner asdescribed with respect to the other double-diaphragm embodiment. Aspigot 138 extends from each of the caps 122′, and is connected to arespective breast pump assembly 16′ via tubing 18 in the mannerpreviously described. It will be noted that the collar 120′ shown inthis embodiment is not exactly the same as collar 120, in that it is notspecifically adapted to receive a diaphragm of the type described withregard to FIGS. 11 and 12, although it could be made so, if desired.Herein, collar 120′ is meant to represent that on a conventional breastpump assembly that could receive a manually driven piston pump, such asshown in U.S. Pat. No. 4,929,229.

[0088] Referring again to FIGS. 14 and 15, this table-topdouble-diaphragm pump utilizes pullers 48″ having a single leg 49″. Asingle hole 65 is provided in the inboard side of each leg 49″, withinwhich pin 134 is rotatably received. Pin 134 is fixed to an eccentric52″, which in turn is fixedly mounted to a drive shaft 44″ rotated bymotor 28″. In this embodiment, motor 28″ is again a DC gear motor. Motor28″ is capable of being driven by a standard rechargeable battery (notshown), such as a NiCd or NiMH camcorder-type battery, which would bemounted in place on the housing in standard well known fashion, as atbattery mounting sidewall 152. An alternative DC adapter for use with anAC power source can be provided (not shown), which would be electricallyconnected at port 154, again using standard circuitry and adaptertechnology which is well known.

[0089] Each puller 48″ has an end disk 60″ which is fixed to a diaphragm70″, as by welding, gluing or the like. The pullers 48″ are reciprocatedin the same manner as previously described under action of the pin 134orbiting on the eccentric 52″. Vacuum is alternatingly generated in therespective breast shield assemblies 16′ in this manner.

[0090] In this table-top embodiment 150, the caps 122′ are each providedwith a vacuum regulation device. This takes the form of a flexible ring160 which is mounted in a channel 161 (FIG. 16) formed in a collarportion 164 that extends outwardly from the cap 122′. Flexible ring 160overlies a vent hole 165 which communicates with the space between theinterior of the cap 122′ and the diaphragm 70″. The flexible ring 160forms an air seal with the channel 161, except for a portion 166comprising a small channel 166 in the ring 160. This small channel 166is rotatable to positions where it will connect one, both or none ofapertures 167 a, 167 b formed in the radially extending outboard lip 164a of the collar portion 164. This respectively will correspond to apreviously determined medium (one aperture), minimum (both) or maximum(neither) vacuum pressure. This pressure regulation is advantageouslyindependently provided for each breast shield in this manner.

[0091] Motor 28″ is actuated by on-off rocker switch 170. It iscontemplated, however, that the motor drive could be modified to includean adjustable speed regulation, such as through use of a circuit havingan adjustable diode arrangement for current control to the motor.

[0092] The embodiment of FIGS. 13 through 18 also provides asound-deadening and vibration-reducing feature. This is provided by softmaterial such as Santoprene supplied by Advanced Elastomer Systems, ofAkron, Ohio. This is a thermoplastic elastomer which is insert-moldedinto each housing half 151 a, 151 b. As shown here, this material isformed in a pyramidal pattern 175 on the broadest part of interiorsidewalls of each half 151 a, 151 b, and in an elongated peak-and-valleypattern 176 along the remainder of each half. Other patterns could beused.

[0093] Feet 176 (FIG. 17) are also molded on the housing valves 151 a,151 b using the same thermoplastic elastomer.

[0094] Most desirably, the sound/vibration reducing material, feet 176and diaphragms 70″, are all insert-molded at the same time with thehousing valves. This greatly reduces and simplifies assembly.

[0095]FIGS. 19 and 20 show designs which would be variants on the typeof diaphragm pump shown in the embodiment of FIGS. 11 and 12. Thesevariants would be single pump versions, i.e., not specifically adaptedfor double-pumping. The FIG. 19 embodiment, for instance, would have ahousing 180 for the elements described with the FIG. 11 and 12 version,except only a single diaphragm pump would be provided. An on-off switchis shown at 181, and mounting collar at 120′. The FIG. 20 embodimentwould likewise include the elements of the FIG. 19 embodiment, but isshown in an alternative mounting arrangement, with the diaphragm pumpmounting collar 120″ extending from the top of the breast shieldassembly.

[0096] In still another variation on a pump for double breast pumping,the embodiment of FIG. 21 is particularly adapted for pumping bothbreasts simultaneously, i.e., negative pressure is transmitted to bothbreasts at the same time. In this proposed version, the motor 28′″ hasan output shaft 44′″ on which an eccentric or cam 52′″ is mounted forrotation as in previous described embodiments. A puller 48′″ is likewisesimilarly mounted to the eccentric 52′″. A guide 40″ is again used tofacilitate movement of the diaphragms 70′″, two of which are employed.Guide 40″ has a channel 45″ into which the motor shaft 44′″ is received.An end of the guide 40″ is fixed to a yoke 190. An end of puller 48′″islikewise fixed to the yoke 190 with a swivel joint connection 191.

[0097] The two diaphragms 70′″pass through a sheet metal frame 192. Theyoke 190 has openings 193 which receive and hold end elements 194 of thediaphragms 70′″. The diaphragms 70′″ are themselves mounted withinorifice 194 formed in a mounting plate 195. Overlying each of thediaphragms 70′″ and fixed, as by screws (not shown), to the mountingplate 195 are plates 24′ having rigid caps 86′ from which extend spigots20′. Diaphragms 70′″ operate in conjunction with the caps 86′ in themanner previously described. The entire pumping mechanism can be mountedwithin a bag 14′, again as in a manner previously described (i.e., FIG.1).

[0098] In operation of the FIG. 21 embodiment, rotation of eccentric52′″ causes the puller 48′″ to orbit the drive shaft 44′″. This actionin turn causes the yoke 190 to move toward and then away from the frame192, to thereby reciprocate the diaphragms 70′″, simultaneouslygenerating a negative pressure in the respective expansible chamberformed by a diaphragm 70′″ and its rigid cap 86′. That negative pressureis communicated through a spigot 20′ to a breast shield assembly viatubing, as previously described.

[0099] While the invention has been described with respect to a numberof embodiments, those with skill in the art will recognize othermaterials, arrangements, modifications and the like which can beadvantageously utilized, yet which will still fall within the scope ofthe inventive concept, and the claims set forth hereinafter.

What is claimed is:
 1. A pump comprising: a flexible diaphragm, a rigidmember, an air seal formed between said diaphragm and said rigid member,a puller member attached to said flexible diaphragm, a drive memberconnected to said puller member which drive member is adapted to drawsaid puller member along with said diaphragm away from said rigidmember, thereby creating a space between said diaphragm and said rigidmember and forming a pressure region within said space, a motor drivemechanism including said drive member to reciprocate said puller memberto first draw said puller member away from said rigid member and thenmove said puller member back toward said rigid member, an outlet incommunication with said space between said diaphragm and said rigidmember, and a vacuum regulator device on said rigid member for adjustingthe level of negative pressure within said pressure region when saiddiaphragm is moved away from said rigid member.
 2. The pump of claim 1wherein said vacuum regulator device comprises a rotary valve membermounted for rotational movement on said rigid member, an aperture beingformed through said valve member, and at least one hole formed throughsaid rigid member in communication with said pressure region, said valvemember having a first position wherein said valve aperture and saidrigid member hole are aligned to place said pressure region incommunication with atmosphere, and a covered position wherein said valveaperture and said rigid member hole are unaligned with said valve memberclosing said rigid member hole.
 3. The pump of claim 2 including asecond hole formed through said rigid member, said valve member having asecond position wherein said valve aperture and said rigid member secondhole are aligned to place said pressure region in communication withatmosphere through said second hole, and wherein said pump has a maximumnegative pressure generated in said pressure region when neither saidfirst and second holes are aligned with said valve aperture, a minimumnegative pressure generated in said pressure region when said secondhole is aligned with said valve aperture, and a negative pressuregenerated in said pressure region intermediate to that of said maximumand said minimum when said first hole is aligned with said valveaperture.
 4. The pump of claim 2 including a second hole formed throughsaid rigid member, said valve member having a second position, saidvalve member having a channel formed therein overlying said rigid memberwith said valve member aperture extending into said channel, and whereinsaid pump has a maximum negative pressure generated in said pressureregion when neither said first and second holes are aligned with saidchannel, a minimum negative pressure generated in said pressure regionwhen said first hole is aligned with said channel, and an intermediatenegative pressure to that of said maximum and minimum is generated whensaid first and second holes are aligned with said channel.
 5. A pumpcomprising: a flexible diaphragm, a rigid member, an air seal formedbetween said diaphragm and said rigid member, a puller member attachedto one of said flexible diaphragm and said rigid member, a drive memberconnected to said puller member which drive member is adapted to drawsaid puller member along with one of said diaphragm and said rigidmember from the other of said diaphragm and rigid member therebycreating a space between said diaphragm and said rigid member andforming a pressure region within said space, a motor drive mechanismincluding said drive member to reciprocate said puller member, an outletin communication with said space between said diaphragm and said rigidmember, and a vacuum regulator device on said rigid member for adjustingthe level of negative pressure within said pressure region when saiddiaphragm is moved away from said rigid member.
 6. A pump comprising: afirst member, a second member movable relative to said first member, anair seal formed between said first and second members, a puller memberattached to said first member, a drive member connected to said pullermember which drive member is adapted to draw said puller member alongwith said first member away from said second member, thereby creating aspace between said first and second members and forming a pressureregion within said space, a motor drive mechanism including said drivemember to reciprocate said puller member to first draw said pullermember away from said second member and then move said puller memberback toward said second member, an outlet in communication with saidspace between said first and second members, and a vacuum regulatordevice on one of said first and second members for adjusting the levelof negative pressure within said pressure region.
 7. A vacuum regulatordevice for a breastpump comprising: a base in communication with avolume which is subject to a source of vacuum; a rotary disk membermounted upon said base; said base having at least one hole formedtherein which extends into said volume; said rotary disk memberoverlying said base and having an aperture therethrough which isalignable with said at least one hole.
 8. A breastpump comprising: firstand second motor driven pumps each generating a negative pressure, withan outlet on each pump communicating with said negative pressure; firstand second breast shield assemblies including tubing for connection to arespective pump; and a vacuum regulator associated with a respectivepump, whereby the negative pressure generated by each said pump isindependently regulatable.
 9. The breastpump of claim 8 wherein eachsaid motor driven pump includes a rigid shell, a flexible diaphragmsealingly mounted to said shell for movement relative to said shell,with a respective vacuum regulator being mounted on said rigid shell.10. A pump for use with a breast shield assembly in the expression ofmother's milk, comprising: a flexible diaphragm, a stationary cap membersurrounding said flexible diaphragm, an air seal formed between saiddiaphragm and said cap member, a puller attached to said flexiblediaphragm, a follower connected to said puller member which follower isadapted to draw said puller member along with said diaphragm away fromsaid cap member, thereby creating a space between said diaphragm andsaid rigid member and forming a negative pressure region within saidspace, a motor drive mechanism including a cam member mounted to turnwith a drive shaft with said follower mounted off-center on said cammember and off-axis to said drive shaft, said cam member when rotated bysaid drive shaft causing said follower to reciprocate said puller memberto first draw said puller member away from said cap member and then movesaid puller member back toward said cap member, and an outlet incommunication with said space between said diaphragm and said cap memberwhich outlet is used to convey a pressure generated in said space, suchas said negative pressure, to a breast shield assembly for use inextracting mother's milk.
 11. The pump of claim 10 further including apair of outlets in communication with said space between said diaphragmand said rigid member, each of said outlets being connectable to arespective breast shield assembly, and a closure member for closing oneof said outlets when said pump is used with a single breast shieldassembly, said closure member including a relief port for allowing apredetermined amount of air to flow into said pressure region when anegative pressure is generated within said pressure region to generallyyield the same negative pressure at a single breast shield assembly aswhen using two breast shield assemblies without said closure.
 12. A pumpcomprising: a flexible diaphragm having a front side and a back side, astationary cap member surrounding said flexible diaphragm front side, anair seal formed between said diaphragm and said cap member, a pullerattached to said flexible diaphragm, a follower pivotably connected tosaid puller member which follower is adapted to draw said puller memberalong with said diaphragm away from said cap member, thereby creating aspace between said diaphragm and said rigid member and forming anegative pressure region within said space, a motor drive mechanismincluding a cam member mounted to rotate with a drive shaft with saidfollower movably mounted off-center on said cam member and off-axis tosaid drive shaft, said cam member when rotated by said drive shaftcausing said follower to reciprocate said puller member to first drawsaid puller member away from said cap member and then move said pullermember back toward said cap member, a puller guide having a channelformed therein, and a guide member which extends into said guide channelfor constrained relative movement within said channel as said pullermember reciprocates, said puller, puller guide and guide membercooperating together to maintain said puller moving along an axisgenerally perpendicular to said diaphragm, and an outlet incommunication with said space between said diaphragm and said cap memberwhich outlet is used to convey a pressure generated in said space to aworkpiece.
 13. The pump of claim 12 wherein a follower is pivotablyconnected to said puller member which follower is adapted to draw saidpuller member along with said diaphragm away from said cap member, saidmotor drive mechanism including a cam member mounted to rotate with adrive shaft with said follower movably mounted off-center on said cammember and off-axis to said drive shaft, said cam member when rotated bysaid drive shaft causing said follower to reciprocate said puller memberto first draw said puller member away from said cap member and then movesaid puller member back toward said cap member, and a stationary guidehaving a channel formed therein, and a guide member mounted on saidpuller member which guide member extends into said guide for constrainedmovement within said channel as said puller member reciprocates.
 14. Thebreastpump of claim 13 further comprising: a vacuum regulatorcommunicating with said space between said diaphragm and said capmember.
 15. The breastpump of claim 14 wherein said vacuum regulatorcomprises a disk which is rotatably mounted on said cap member, saiddisk having an aperture formed therethrough which is selectivelyalignable with at least one opening through said cap member andextending into said space between said diaphragm and cap member.
 16. Thebreastpump of claim 14 wherein said vacuum regulator device comprises arotary valve member mounted for rotational movement on said cap member,an aperture being formed through said valve member, and at least onehole formed through said rigid member in communication with saidpressure region, said valve member having a first position wherein saidvalve aperture and said rigid member hole are aligned to place saidpressure region in communication with atmosphere, and a covered positionwherein said valve aperture and said rigid member hole are unalignedwith said valve member closing said rigid member hole.
 17. Thebreastpump of claim 16 including a second hole formed through said rigidmember, said valve member having a second position wherein said valveaperture and said rigid member second hole are aligned to place saidpressure region in communication with atmosphere through said secondhole, and wherein said pump has a maximum negative pressure generated insaid pressure region when neither said first and second holes arealigned with said valve aperture, a minimum negative pressure generatedin said pressure region when said second hole is aligned with said valveaperture, and a negative pressure generated in said pressure regionintermediate to that of said maximum and said minimum when said firsthole is aligned with said valve aperture.
 18. A pump mechanism for abreastpump comprising: a motor drive having a drive shaft output; aneccentric mounted to be rotated by said drive shaft output; a first anda second puller; a first and a second expansible chamber, each saidexpansible chamber having a flexible diaphragm which is movable relativeto a base member and is generally air sealed with respect to said basemember so as to form a variable volume with said base member by movementof said diaphragm, each said diaphragm having a front side and a backside; an outlet in communication with a variable volume of a respectivechamber; said first puller being connected to said first expansiblechamber to move its flexible diaphragm relative to a respective basemember, and said second puller being connected to said second expansiblechamber to move its flexible diaphragm relative to a respective basemember, said first and second pullers being connected to be moved bysaid eccentric in a push-pull arrangement, whereby as said eccentric isrotated one expansible chamber has a decreasing volume and the otherexpansible chamber has an increasing volume.
 19. The pump mechanism ofclaim 18 wherein said first puller is connected to said flexiblediaphragm of said first expansible chamber, said second puller isconnected to said flexible diaphragm of said second expansible chamber,each said puller being pivotably mounted to said eccentric and extendingin generally opposite directions from said eccentric with saidexpansible chambers on generally opposite sides of said eccentric, withsaid eccentric being mounted to said drive shaft.
 20. The pump mechanismof claim 19 wherein each said base member is a rigid cap within which arespective diaphragm is received to move relative to a cap interiorwall, said rigid cap for said first expansible chamber being formedintegral with a breast shield assembly and the other rigid cap for saidsecond expansible chamber being mounted to a pump mechanism housing,with said outlet of said second expansible chamber communicating with asecond breast shield assembly via tubing.
 21. The pump mechanism ofclaim 19 wherein each said base member is a rigid cap within which arespective diaphragm is received to move relative to a cap interiorwall, each said rigid cap being formed in a pump mechanism housing, withsaid outlets of said first and second expansible chambers communicatingwith a respective breast shield assembly via tubing.
 22. A pumpmechanism for a breastpump comprising: a motor drive, a first and asecond puller; a mechanism connecting said first and second puller tosaid motor drive; a first and a second expansible chamber, each saidexpansible chamber having a first member which is movable relative to abase member and is generally air sealed with respect to said base memberso as to form a variable volume with said base member by movement ofsaid first member, a first outlet in communication with the variablevolume of said first chamber and a second outlet in communication withthe variable volume of said second chamber; said first puller beingconnected to said first expansible chamber to move its first memberrelative to a respective base member, and said second puller beingconnected to said second expansible chamber to move its first memberrelative to a respective base member, said first and second pullersbeing connected to be moved in a push-pull arrangement by said by saidmechanism, whereby as said motor is operated one expansible chamber hasa decreasing volume and the other expansible chamber has an increasingvolume.
 23. A pump mechanism for a breastpump comprising: a motor drive;a first and a second expansible chamber, each said expansible chamberhaving an element which is movable relative to a base member with saidelement and base member being generally air sealed with respect to eachother so as to form a variable volume between them by movement of saidelement relative to said base member, with an outlet in communicationwith a respective variable volume; and a drive train being connected tosaid motor drive and to said first and second expansible chambers tomove each expansible chamber element relative to a respective basemember.
 24. The pump mechanism of claim 23 wherein said element is aflexible diaphragm and said base member is a rigid member to which saiddiaphragm is mounted and having a respective outlet formed in said rigidmember, said diaphragm being moved in relation to said rigid member by adrive train including an eccentric which is rotated by said motor drive,with a first puller mounted to move with said eccentric and connected tothe diaphragm of said first expansible chamber, and a second pullermounted to move with said eccentric and connected to the diaphragm ofsaid second expansible chamber, said first and second pullers extendingin generally opposite directions from said eccentric so as to expand thevolume of one expansible chamber while contracting the volume of theother expansible chamber as said eccentric rotates.
 25. The pumpmechanism of claim 23 wherein said element is a flexible diaphragm andsaid base member is a rigid member to which said diaphragm is mountedand having a respective outlet formed in said rigid member, saiddiaphragm being moved in relation to said rigid member by a drive trainincluding an eccentric which is rotated by said motor drive, with apuller mounted to move with said eccentric and connected to a yoke, thediaphragms of said first and second expansible chambers being connectedto said yoke so as to expand and contract the volumes of said expansiblechambers in tandem as said eccentric is rotated.
 26. A pump mechanismfor a breastpump comprising: a motor drive; a first and a secondexpansible chamber, each said expansible chamber having an element whichis movable relative to a base member with said element and base memberbeing generally air sealed with respect to each other so as to form avariable volume between them by movement of said element relative tosaid base member; a first outlet in communication with the variablevolume of said first chamber and a second outlet in communication withthe variable volume of said second chamber; a drive train connected tosaid motor drive and to said first and second expansible chambers tomove each expansible chamber element relative to a respective basemember, and a housing for said motor drive, expansible chambers anddrive train; said housing, said motor drive, said first and secondchambers and said drive chain being arranged in a hand-held unit. 27.The pump mechanism of claim 26 wherein the base member of said firstexpansible chamber is a rigid cap attached to a first breast shieldassembly within which the element of said first expansible chamber isreceived in sealing engagement, with said pump mechanism thereby beingcarried by said first breast shield assembly, and the base member ofsaid second expansible chamber is a rigid cap within which the elementof said second expansible chamber is received in sealing engagement, andfurther including tubing connecting the outlet of said second expansiblechamber with a second breast shield assembly.
 28. The pump mechanism ofclaim 27 wherein said element is a flexible diaphragm, said diaphragmbeing moved in relation to said cap member by a drive train including aneccentric which is rotated by said motor drive, with a first pullermounted to move with said eccentric and connected to the diaphragm ofsaid first expansible chamber, and a second puller mounted to move withsaid eccentric and connected to the diaphragm of said second expansiblechamber, said first and second pullers extending in generally oppositedirections from said eccentric so as to expand the volume of oneexpansible chamber while contracting the volume of the other expansiblechamber as said eccentric rotates.
 29. A pump mechanism for a breastpumpcomprising: a motor drive; a first and a second expansible chamber, eachsaid expansible chamber having an element which is movable relative to abase member with said element and base member being generally air sealedwith respect to each other so as to form a variable volume between themby movement of said element relative to said base member; an outlet foreach variable volume of a respective chamber; a drive train connected tosaid motor drive and to said first and second expansible chambers tomove each expansible chamber element relative to a respective basemember, and a housing having each said base member integrally formedtherein, said housing further containing said motor drive, expansiblechambers and drive train.
 30. The breastpump of claim 29 wherein eachsaid base member is a rigid hemispherical cap respectively formed inopposite sidewalls of said housing, the element of a respective firstand second expansible chamber being received in sealing engagement withits respective cap, and further including tubing connecting the outletof each said first and second expansible chamber with a respectivebreast shield assembly.
 31. The breastpump of claim 30 wherein saidelement is a flexible diaphragm, said diaphragm being moved in relationto said cap by a drive train including an eccentric which is rotated bysaid motor drive, with a first puller mounted to move with saideccentric and connected to the diaphragm of said first expansiblechamber, and a second puller mounted to move with said eccentric andconnected to the diaphragm of said second expansible chamber, said firstand second pullers extending in generally opposite directions from saideccentric so as to expand the volume of one expansible chamber whilecontracting the volume of the other expansible chamber as said eccentricrotates.
 32. A housing for a pump mechanism of a breastpump comprising:first and second housing parts which assemble to provide an interiorspace for containing pump mechanism components; and a noise andvibration reducing material formed integral with said housing partsadjacent said interior space.
 33. The housing of claim 32 furtherincluding a flexible diaphragm formed integral with each housing part.34. A housing for a pump mechanism of a breastpump comprising: first andsecond housing parts which assemble to provide an interior space adaptedto contain pump mechanism components, and a flexible diaphragm formedintegral with each housing part.
 35. The housing of claim 34 whereinsaid flexible diaphragm is fixed within an opening defined in arespective housing part, and further including a rigid hemispherical capmember which is removably and sealingly mountable over said opening onthe outboard side of each housing part, said cap member and respectivediaphragm together forming an expansible chamber for generating airpressure variations therein.
 36. The housing of claim 35 furtherincluding a noise and vibration reducing material formed integral withsaid housing parts adjacent said interior space.
 37. A housing for apump mechanism of a breastpump comprising a flexible diaphragm formedintegral with the housing.
 38. The housing of claim 37 wherein saidflexible diaphragm is fixed within an opening defined in a respectivehousing part, and further including a rigid hemispherical cap memberwhich is removably and sealingly mountable over said opening on theoutboard side of each housing part, said cap member and respectivediaphragm together forming an expansible chamber for generating airpressure variations therein.
 39. The housing of claim 38 furtherincluding a noise and vibration reducing material formed integral withsaid housing parts adjacent said interior space.